Volumetric pump/valve

ABSTRACT

A volumetric pump for administering intravenous fluids to a patient comprises a housing having an elongate cavity therein with an open and a closed end. A resilient sheet of material having a centrally-located aperture covers the open end, and a pump shaft is slidably disposed through the aperture to form a sphincter seal therebetween. An inlet conduit leading from a fluid source (an IV bag) passes through the housing into the cavity near the open end thereof, and an outlet conduit leading to a fluid sink (the patient) passes through the housing from the cavity near the closed end thereof. The shaft is driven back and forth in reciprocating motion inwardly and outwardly of the cavity to produce, respectively, a positive pressure forcing fluid out of the outlet conduit to the fluid sink, and a negative pressure forcing fluid from the fluid source through the inlet conduit.

BACKGROUND OF THE INVENTION

This invention relates to a lightweight, inexpensive volumetric pump,suitable for a variety of uses including medical systems such asintravenous (IV) therapy systems and the like.

The intravenous administration of fluids to patients is a well-knownmedical procedure for, among other things, administering life sustainingnutrients to patients whose digestive tracts are unable to functionnormally due to illness or injury, administering antibiotics to treat avariety of serious infections, administering analgesic drugs to patientssuffering from acute or chronic pain, administering chemotherapy drugsto treat patients suffering from cancer, etc.

The intravenous administration of drugs frequently requires the use ofan IV pump connected or built into a so-called IV administration setincluding, for example, a bottle of fluid to be administered andtypically positioned upside down, a sterile plastic tubing set, and apump for pumping fluid from the bottle through the IV set to thepatient. Other mechanisms may be included to manually stop the flow offluid to the IV feeding tube and possibly some monitoring devices.

Current IV pumps generally are of two basic types: electronic pumps anddisposable non-electronic pumps. Although the electronic pumps have beensignificantly miniaturized and do include some disposable components,they are nevertheless generally high in cost, require frequentmaintenance with continued use, and may be difficult for a layman tooperate if, for example, self treatment is desired.

The disposable non-electric pumps generally consist of small elastomericbags within a hard shell container, in which the bags are filled with IVsolution under pressure. The pressure generated by the contraction ofthe elastomeric bag forces the IV solution through a fixed orifice at aconstant flow rate into the patient's vein. Although these pumps aremuch less expensive than the electronic pumps and eliminate the need formaintenance (since they are discarded after every use), their drawbacksinclude the lack of monitoring capability, the lack of the ability toselect different flow rates, limited fluid capacity, and stillrelatively high cost for a disposable product.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a new and improvedvolumetric pump which is especially suitable for use in IVadministration sets, other medical systems, and the like.

It is also an object of the invention to provide such a pump configuredto sweep bubbles from the pump chamber during operation.

It is a further object of the invention to provide such a pump which iseasy to manufacture and utilizes low cost parts.

It is another object of the invention to provide such a pump design inwhich tight tolerances are not required.

It is also an object of the invention to provide such a pump which isefficient and reliable.

It is an additional object of the invention to provide such a pump whichmay be readily miniaturized.

It is still another object of the invention, in accordance with oneaspect thereof, to provide such a pump whose flow rate may be readilychanged.

It is a further object of the invention to provide valves, drivingmechanisms, control methods, programming methods and apparatus, andpressure detectors suitable for use with the pump.

The above and other objects of the invention are realized in a specificillustrative embodiment of a pump which utilizes a simplecircumferential polymeric seal, or sphincter seal to retain and preventloss or leaking of the fluid being pumped. One illustrative embodimentof the invention includes a housing defining an elongate cavity therein,with an opening on one side of the housing adjacent to and incommunication with the one end, the other end being closed. Alsoincluded is a resilient sheet of material disposed over the opening inthe housing, with the sheet including an aperture positioned inalignment with the cavity at the one end thereof. An elongate shaft isslidably disposed in the aperture so that one end of the shaft extendsinto the cavity and the other end extends out of the housing. Theaperture has substantially the same cross-sectional shape as that of theshaft, and the same cross-sectional dimensions or smaller. An inlet isprovided in the housing, through which fluid from a fluid source mayflow into the cavity, and an outlet is also provided in the housing,through which fluid may flow from the cavity to a fluid sink. Theresilient sheet of material surrounds and grips the shaft at theaperture in the sheet to provide a sphincter seal which prevents fluidfrom flowing through the aperture but allows the shaft to slidelongitudinally therein.

When the shaft is moved in a direction outwardly of the housing, anegative pressure is produced in the cavity to draw in fluid through theinlet, and when the shaft is moved further into the cavity, a positivepressure is produced in the cavity to force fluid from the cavitythrough the outlet. Valves may be provided in or near the inlet andoutlet to allow fluid only to flow into the cavity through the inlet andout of the cavity through the outlet.

A variety of driver mechanisms and control methods may be provided tocause the shaft to reciprocate within the cavity to produce the pumpingaction, including ratchet drives, magnetic linear step motors,rotary-to-linear crank drives, and screw drive mechanisms.

A variety of valves using sphincter seals and similar mechanisms may beprovided to control fluid flow in the pump, among other mechanisms, andelectro-mechanical sensors may be provided to detect over- orunderpressure of fluid in the pump, or other mechanisms.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the inventionwill become apparent from a consideration of the following detaileddescription presented in connection with the accompanying drawings inwhich:

FIG. 1 is a perspective view of a volumetric pump, using a sphincterseal, made in accordance with the principles of the present invention.

FIG. 1A is a fragmented, side, cross-sectional view of a preferredembodiment of front and rear supports to prevent degradation andwaffling of the sphincter seal;

FIG. 1B is a fragmented, side, cross-sectional view of anotherembodiment of a volumetric pump made in accordance with the principlesof the present invention;

FIG. 1C is a fragmented end view along line 1C--1C of FIG. 1B;

FIG. 2 is a fragmented, side, cross-sectional view of one embodiment ofa drive/pump shaft interface for stopping the pumping action if toolittle or too much pressure is created in the pump cavity;

FIG. 3 is a side, cross-sectional, schematic view of another embodimentof a volumetric pump made in accordance with the principles of thepresent invention;

FIG. 4 is a side, cross-sectional view of a volumetric pump made inaccordance with the principles of the present invention, incorporated ina hypodermic needle;

FIG. 5 is a side, cross-sectional view of still another embodiment of avolumetric pump made in accordance with the principles of the presentinvention;

FIG. 6 is a side, cross-sectional view of a further embodiment of avolumetric pump made in accordance with the principles of the presentinvention;

FIG. 6A is a side, cross-sectional view of an embodiment of a volumetricpump similar to that illustrated in FIG. 6, but with a different drivesystem;

FIG. 6B is a side, cross-sectional view of a further embodiment of avolumetric pump similar to that illustrated in FIG. 6, but with stillanother drive system;

FIG. 6C is a side, cross-sectional view of an additional embodiment of avolumetric pump similar to that illustrated in FIG. 6, again with adifferent drive system;

FIG. 7 is a side, cross-sectional view of a valve utilizing sphincterseals, made in accordance with the principles of the present invention;

FIG. 8 is a side, cross-sectional view of another embodiment of a valve,also utilizing sphincter seals, made in accordance with the principlesof the present invention;

FIG. 9 is a side, cross-sectional view of a spool valve mechanism foruse in volumetric pumps of the present invention for controlling theflow of fluid;

FIGS. 10, 11, 12, 13 and 13A show five illustrative embodiments of drivemechanisms which may be utilized for driving the pump shaft of thevolumetric pumps of the present invention;

FIG. 14 shows a side, cross-sectional view of a fluid pressure detectorfor use with volumetric pumps of the present invention, among others;

FIG. 15 is a side, cross-sectional view of a further embodiment of afluid pressure detector;

FIG. 16 is a side, cross-sectional view of yet a further embodiment of afluid pressure detector;

FIG. 17 is a side, cross-sectional view of a ball valve for use withvolumetric pumps of the present invention, among others;

FIG. 18 is a view along line 18--18 in FIG. 17;

FIG. 19 is a side, cross-sectional view of a plunger bottoming detectoraccording to the invention;

FIG. 20 is a side, cross-sectional view of another embodiment of a valveaccording to the invention;

FIG. 21 is a side, cross-sectional view of another embodiment of a sealaccording to the invention;

FIG. 22 is a top, schematic view of a programming card system forcontrolling the driving mechanism in the present invention;

FIG. 23 is a side, cross-sectional view of the programming card systemof FIG. 22;

FIG. 24 is a fragmented, side, cross-sectional view of a spring assistedseal arrangement suitable for use in the present invention;

FIG. 25 is a fragmented, side, cross-sectional view of a duplex,inwardly turned sphincter seal arrangement suitable for use in thepresent invention; and

FIG. 26 is a fragmented, side, cross-sectional view of a duplex,outwardly turned sphincter seal arrangement suitable for use in thepresent invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, there is shown a perspective view of a volumetricpump made in accordance with the present invention to include agenerally elongate housing 4, formed with an elongate cavity 8 therein(refer to FIG. 3 which also shows the housing 4 and the elongate cavity8). The housing 4 might illustratively be formed with an exterior shell12 made of metal or hard plastic, and an interior filler 16 disposedagainst the shell 12, with the cavity 8 formed centrally therein. Thefiller could similarly be metal or hard plastic.

Disposed in one end of the housing 4 is a resilient sheet of material 20made, for example, of latex rubber, silicone rubber, or nitrile rubber.The sheet of material 20 fills the end of the housing 4 to preventcommunication between the outside of the housing and the cavity 8 exceptthrough an aperture 24 positioned in line with the cavity 8.

An inlet duct 28 is formed in the housing 4 generally adjacent to thesheet of material 20, to communicate with the cavity 8, and an outletduct 32 is similarly formed in the housing to communicate with thecavity at the other end thereof (FIG. 3). Conduits 36 and 40respectively couple ducts 28 and 32 to a fluid source 44 and a fluidsink 48 (FIG. 1). Check valves 52 and 56 are disposed respectively inconduits 36 and 40 to allow fluid to flow from the fluid source 44 intothe cavity 8 and prevent the reverse flow, and to allow fluids to flowfrom the cavity 8 to the fluid sink 48 and prevent the reverse flow. Thefluid source 44 could be any source of fluid which it is desired to bepumped to fluid sink 48, such as an IV administration set which includesa bottle of fluid to be administered to a patient, with the fluid source44 being the bottle and the fluid sink 48 being the patient receivingthe fluid. Of course, as will be evident upon further discussion, thefluidic pump of FIG. 1 could be used in a variety of environments.

An elongate shaft or plunger 60 is disposed in the aperture 24 of thesheet of material 20 to extend at least partially into the cavity 8(FIG. 3) of the housing 4. The shaft 60 may have a circular crosssection and have a somewhat smaller circumference than that of thecavity 8 so that the shaft may be moved in a reciprocating fashion backand forth in the aperture 24 and cavity 8. The aperture 24 is preferablyshaped similarly to the cross-sectional shape of the shaft 60 and ispreferably the same or slightly smaller in size in order to completelysurround and grip the shaft to form a sphincter seal and prevent fluidfrom escaping the cavity 8. As the aperture is formed in the resilientsheet of material 20, the aperture conforms to the shape of the shaft 60even if their shapes are not identical, though it will be obvious tothose skilled in the art that the more the shapes differ the lesseffective the seal will be.

Disposed on the free end of the shaft 60 is a bumper pad 64 (FIG. 1). Acoil spring 68 is disposed about that portion of the shaft 60 which isoutside of the housing to provide a bias force against the bumper pad 64to urge the shaft outwardly from the housing.

A support rod 72 is mounted on the top of the housing 4 and extendsforwardly therefrom, and a stopper finger 76 is slidably mounted on therod 72 so that it may be slid forwardly or rearwardly along the rod. Aset screw 80 is provided in the stopper finger 76 to allow for settingor fixing the position of the stopper finger on the rod. Stopper finger76 extends downwardly to a position in the pathway of possible movementof the bumper pad 64 to prevent the bumper pad and thus the shaft 60from moving outwardly from the housing 4 beyond the location of thestopper finger. FIG. 1 shows the bumper pad 64 resting against the lowerend of the stopper finger 76 to illustrate that the bumper pad 64 andshaft 60 are prevented from moving any further outwardly from thehousing 4. The setting of the stopper finger 76 by means of the setscrew 80 determines the stroke or excursion of movement of the shaft 60within the cavity 8 of the housing 4.

A driving mechanism 84, such as a solenoid, is positioned in front ofthe housing 4 so that a solenoid drive core 88 extends toward the bumperpad 64 as shown. When the drive mechanism 84 is activated (for exampleby applying an electrical current to a solenoid), the driver core 88 iscaused to move towards the bumper pad 64, engage it and move the bumperpad and the shaft 60 toward the housing 4 so that the shaft movesfurther into the cavity 8 of the housing. When the drive mechanism 84 isdeactivated, the drive core 88 retracts into the drive mechanism 84allowing the coil spring 68 to urge the bumper pad 64 and thus the shaft60 outwardly from the housing until the bumper pad contacts the stopperfinger 76. Alternative activation and deactivation of the drivemechanism 84 will thus result in the shaft 60 being reciprocated withinthe cavity 8 of the housing 4.

In operation, when the shaft 60 is moved further into the cavity 8, anyfluid within the cavity is forced into the conduit 40 and through thecheck valve 56 to the fluid sink 48. When the shaft is allowed toretract or move outwardly of the cavity 8, a negative pressure iscreated in the cavity, causing fluid to be drawn from the fluid 44through the check valve 52 and into the cavity. The continuedreciprocation of the shaft 60 thereby provides for pumping fluids fromthe fluid source 44 to the fluid sink 48.

One advantage to the pumps shown in FIGS. 1 and 3 is that the shapes ofthe plunger and cavity cause gas bubbles to be swept out of the cavitywith each stroke of the plunger, instead of accumulating in the cavity,especially around the seal made in the sheet 20. This allows for greatervolumetric accuracy in the pumping action.

FIG. 1A shows a fragmented, side, cross-sectional view of the shaft 60,the aperture 24 in the resilient sheet 20, with the addition of forwardand rear seal supports 90 and 92. The supports 90 and 92 allow forgreater positive or negative fluid pressure in the cavity 8 bysupporting the sheet 20 at the aperture 24 so that it does not distendwith the movement of the shaft 60 into the cavity (to thus stretch anddegrade the resilient material and damage the seal), or collapse withthe movement of the shaft 60 out of the cavity (to further degrade thematerial and damage the seal). Greater fluid pressure in the cavityexacerbates the problems of distending and collapsing the sheet 20,which the supports 90 and 92 help prevent.

The rear support 92 preferably comprises an inflexible flat plate withan aperture 92a formed therein. The aperture 92a is preferably similarin shape and slightly larger in size than the shaft 60 to allow freemovement of the shaft therein, and is located close to the sheet 20.During movement of the shaft 60 into the cavity 8, the friction of theshaft 60 against the sheet 20 at the aperture 24 tends to cause thelatter to distend toward the cavity 8. The sheet 20 at the aperture 24,however, contacts the support 92 before distending enough to damage thematerial or loosen the seal.

Like the support 92, the support 90 preferably comprises a plate with anaperture 90a formed therein, but also a lip 90b around the aperture,extending toward the cavity 8. The lip is preferably shaped toapproximate the shape of the sheet 20 at the aperture 24 after the shaft60 has been inserted therein. During movement of the shaft 60 out of thecavity 8, the fluid pressure in the cavity and the friction of the shaft60 against the sheet 20 at the aperture 24 tend to cause the aperture tocollapse upon itself in a direction away from the cavity 8. The support90, however, prevents collapsing and maintains the desired position ofthe sheet 20 at the aperture 24 during withdrawal of the shaft 60 fromthe cavity 8. The support 90 also bears a large amount of fluid pressurefrom the cavity 8, relieving somewhat the pressure on the sheet 20.

FIG. 1B shows another pump similar to that shown in FIG. 1 except thatthe cavity 8 is close to the shape and size of the plunger 60 in crosssection except for a trough 94 which runs adjacent the length of thecavity. Also, the cavity 8 is enlarged in an area 8a around thesphincter seal to be in fluid communication with an inlet conduit 36,such that fluid can flow from the conduit 36 into the cavity 8 andtrough 94 even when the plunger 60 is inserted into the cavity.

The pumping action in the embodiment of FIG. 1B is the same as in FIGS.1, and the cavity 8 shape and size with trough 94 helps to furthereliminate bubbles from low-flow areas in the cavity.

FIG. 2 shows a fragmented, side, cross-sectional view of one embodimentof a drive/pump shaft interface for terminating the pumping action iftoo little or too much pressure is created in the pump cavity 8. Theshaft 60 is slidably disposed in the cavity 8 and extends outwardlythrough an aperture 24 in the resilient sheet of material 20 toterminate at a free end 60a. Disposed on the free end 60a of the shaft60, which is made of a ferro-magnetic material, is a magnet cap 100. Themagnet cap 100 is magnetically attracted to the free end 60a of theshaft 60 to remain in place until a force greater than the magneticattraction force pulls the magnet cap from off the free end 60a of theshaft 60. Formed on the end of a driver core 88 is a bracket 104, madeof a ferro-magnetic material, which branches into two fingers outwardlyand then behind the magnet cap 100, to positions in contact with a rearsurface of the magnet cap. The two fingers of the bracket 104 aremagnetically attracted into contact with the magnet cap 100 and willremain in contact until a force greater than the magnetic force ofattraction is applied to the bracket in a direction toward the housing4.

With the structure shown in FIG. 2, the pumping action of movement ofthe shaft 60 in the cavity 8 will be stopped if a resistance force tomovement of the shaft is encountered either in pushing the shaft furtherinto the cavity 8 or pulling the shaft outwardly of the cavity. Inparticular, if the resistance force to pulling the shaft 60 outwardly ofthe cavity 8 exceeds the force of attraction of the magnet cap 100 tothe free end 60a of the shaft, the magnet cap will be pulled from offthe free end by the bracket 104, and the pumping action will stop.Likewise, if the resistance force to pushing the shaft 60 further intothe cavity 8 exceeds the force of magnetic attraction of the bracket 104to the magnet cap 100, then the bracket will be pushed free from contactwith the magnet cap and, again, the pumping action will stop. Theadvantage of this arrangement is that unexpected resistance to pumping,such as a clogged inlet or a clogged outlet, or other clogging in thefluid pathway, will result in the pumping action being stopped. Thestopping of the pumping action could also be used to alert the pump userof a problem in the fluid pathway.

FIG. 3 is a side, cross-sectional, schematic view of another embodimentof a volumetric pump in which the same housing structure 4 as that ofFIG. 1 is employed. In this case, however, valves 110 and 114, disposedrespectively in conduits 36 and 40, are not check valves as in FIG. 1,but rather are controlled by a control unit 118. The valves 110 and 114still control the flow of fluid from a fluid source 44 to the cavity 8and from the cavity 8 to a fluid sink 48, but this is all done undercontrol of the control unit 118.

The control unit 118 also controls operation of an electric motor 122whose drive shaft 126 is coupled to a drive wheel 130. As the motor 22operates to rotate the drive shaft 126, the wheel 130 is rotated. Adrive nipple 134 is mounted near the perimeter of the drive wheel 130and is pivotally coupled to one end of a drive shaft 138 which, in turn,is pivotally coupled at its other end to the free end of the pump shaft60. As the drive wheel 130 is caused to rotate, the drive shaft 138 iscaused to reciprocate back and forth and, in turn, cause the shaft 60 toreciprocate in the cavity 8.

A second housing 140 is provided in the preferred embodiment around thehousing 4, pump shaft 60, drive shaft 138, drive wheel 130, and aportion of the drive shaft 126, to seal the components from outsidecontamination or interference. The housing 140 preferably comprisesrigid material such as steel or plastic except around the drive shaft126, where it comprises a sheet of resilient material 142, similar tothe sheet 20, with an aperture 144 formed therein to create a sphincterseal on the drive shaft 126 similar to the seal of the sheet 20 aroundthe pump shaft 60. However, in the case of the drive shaft 126, thesheet 142 at the aperture 144 seals the drive shaft 126 duringrotational, rather than reciprocal, movement.

In operation, the control unit 118 causes the motor 122 to operate androtate, with the angular position of the drive shaft 126 being fed backto the control unit. Based on the angular position of the drive shaft126 and thus the drive wheel 130, the control unit will cause valves 110and 114 to alternately open and close to allow fluid to flow from thefluid source 44 into the cavity 8 on the withdrawal stroke or movementof the shaft 60, and allow fluid to flow from the cavity 8 to the fluidsink 48 on the pump stroke of the shaft 60. In effect, more directcontrol of the opening and closing of the valves 110 and 114 is providedto ensure more effective pumping of fluid from the fluid source 44 tothe fluid sink 48 by preventing free flow caused when both valves areopen at the same time (which might occur, for example, if the fluidsource were an IV bag and IV bag was squeezed). The control unit 118might illustratively be any conventional microprocessor used forcontrolling operation of electrical equipment.

FIG. 4 shows a side, cross-sectional view of a volumetric pump accordingto the invention, incorporated into a hypodermic needle 150. Theembodiment of FIG. 4 may be used, for example, to pump medicationdirectly into a patient's bloodstream without the need for interveningtubes and the like.

The needle 150 has an elongate interior cavity 152 and an open outletend 154. A resilient sheet of material 20 is disposed over the oppositeend of the needle, and a shaft or plunger 60 is disposed through anaperture in the sheet 20 for movement inwardly and outwardly of thecavity 152, in the same manner as previously described with regard toFIGS. 1 through 3.

An inlet conduit 156 extends through the side of the needle 150 into thecavity 152 for supply of a fluid into the cavity from a fluid source 44.A valve 52, which may be a mechanical check valve or electronicallycontrolled valve as have been previously described, is located in theinlet conduit 156 and allows fluid to flow from the fluid source throughthe inlet conduit to the cavity 152, while preventing flow in theopposite direction. A similar valve 158 is provided in the cavity 152forwardly of the shaft 60 to allow forward movement of fluid from theshaft to the outlet end 154 of the needle, while preventing flow in theopposite direction.

In operation, when the shaft 60 is moved rearwardly (outwardly) from thecavity 152 under power of a drive means (not shown but described in thisspecification or other suitable drive means), it creates a negativepressure in the cavity 152, causing fluid from the fluid source 44 toenter the inlet conduit 156 and pass through the valve 52 into thecavity 152. When the shaft 60 reverses direction and moves forwardly(inwardly) into the cavity 152, it creates a positive pressure thatpushes the fluid in the cavity through the valve 158 out the outlet end154 of the needle and into, for example, the patient in which the needleis inserted.

With the repetition of this process, medication or other fluid can besteadily pumped directly into a patient.

FIG. 5 is a fragmented, side, cross-sectional view of another embodimentof a volumetric pump in accordance with the invention. The elongatehousing 172 of the pump contains two interior cavities: an inlet cavity174 at the rear of the housing and an outlet cavity 176 at the front ofthe housing. A passage 178 provides communication between the twocavities. A sheet of resilient material 20 is disposed in the inletcavity 174, closing off a portion of the cavity such that the onlyopenings to it are an aperture 24 in the sheet 20 and the passage 178.

An elongate pump shaft or plunger 180 is disposed in the inlet cavity174 through the aperture 24 forming a sphincter seal as previouslydescribed. A drive bracket 182, driven by suitable drive means (notshown), is connected to the pump shaft 180 and moves the latter back andforth in reciprocal movement inwardly and outwardly of the inlet cavity174. As in previously-described embodiments, the drive bracket 182 doesnot move the pump shaft 180 so far as to pull it out of the sphincterseal.

A forward portion 180a of the pump shaft 180, which extends through thesphincter seal formed by the resilient sheet 20 and aperture 24 andwhich is connected to the drive bracket 182, is rigid in the preferredembodiment. A rear portion 180b of the pump shaft is flexible. One endof the rear portion 180b attaches to the forward portion 180a, while theother end attaches to a fluid source (not shown). The rear portion 180bof the pump shaft is flexible to accommodate the reciprocating movementof the forward portion of the shaft while enabling it to remainconnected to a stationary fluid source.

An inlet conduit 184 is formed in the pump shaft 180 for supplying fluidfrom the fluid source into the inlet cavity 174. A plug 186 is disposedat the end of the inlet conduit 184 in the inlet cavity. The plug isconnected by a coil spring 188 to a pin 190 fixed in the interior of theinlet conduit 184, the arrangement being configured such that the springurges the plug against the opening of the inlet conduit 184 absent otherforces.

In the outlet cavity 176, a second plug 192 is urged against the passage178 under force of a coil spring 194 attached at one end to the plug 192and at the other to a pin 196 fixed in the outlet cavity. Absent otherforces, the plug 192 closes communication via the passage between theinlet cavity 174 and the outlet cavity 176.

In operation, when the drive bracket 182 moves the pump shaft 180rearwardly (outwardly) from the inlet cavity 174, the movement creates anegative pressure in the cavity since it is closed off by the plug 192and the sheet 20. This negative pressure creates a pressure differentialbetween the cavity and the fluid-filled inlet conduit 184, which, in thepreferred embodiment, overcomes the force of the spring 188 and forcesthe plug 186 off its seat on the end of the inlet conduit, causing fluidto flow from the inlet conduit into the cavity 174.

When the pump shaft 180 reverses direction and moves forwardly(inwardly) into the cavity 174, it creates a positive pressure in thecavity 174 which pushes the plug 186 back on its seat with theassistance of the spring 188. The positive pressure also overcomes theforce of the spring 194 holding the plug 192 against the passage 178,forcing the plug back and allowing fluid to flow from the inlet cavity174 into the outlet cavity 176, and from there to, for example, a fluidsink or patient.

When the shaft's movement again reverses, in addition to forcing theplug 186 from its seat on the inlet conduit 184, it causes the plug 192to again be seated against the passage 178. During forward movement ofthe shaft, therefore, the plug 192 is unseated while the plug 186 isseated. During rearward movement of the shaft, the plug 192 is seatedwhile the plug 186 is unseated.

FIG. 6 is a fragmented, side, cross-sectional view of a furtherembodiment of a volumetric pump according to the invention. In thisembodiment, a fluid inlet passage 200 formed of suitable tubing orpiping leads from a fluid source (not shown) into dual inlet conduits202 and 204, each having a check valve 206 for prevention of backwardflow. The inlet conduits are connected to opposite ends of an elongatehousing 208 which contains interior cavities 210 and 212 which, in turn,are separated by a sheet 20 of resilient material disposed in thehousing. The inlet conduit 202 leads into the cavity 210, while theinlet conduit 204 leads into the cavity 212.

An elongate pump shaft 60 is disposed within the two cavities andthrough an aperture 24 in the sheet 20, forming a sphincter seal aspreviously described. A drive shaft 214 attaches to one end of the pumpshaft 60 to drive the pump shaft back and forth within the cavities 210and 212 and through the sheet 20. The drive shaft 214 is powered by anysuitable drive means apparent to those skilled in the art in light ofthis disclosure.

A resilient sheet of material 20a, having an aperture 24a is disposed atone end of the housing 208, through which the drive shaft 214 passes,forms a sphincter seal as previously described.

Outlet conduits 216 and 218 lead out of the cavities 210 and 212,respectively, into a combined fluid outlet passage 220. Like the inletconduits, each outlet conduit 216 and 218 has a check valve 206 forprevention of backward flow of fluid.

In operation, when the drive shaft 214 moves the pump shaft 60 more intothe cavity 210 and out of the cavity 212, a negative pressure is createdin the cavity 212, drawing fluid from the inlet conduit 204 into thecavity 212. At the same time, a positive pressure is created in thecavity 210, pushing the fluid contained therein into the outlet conduit216 and fluid outlet 220.

The valves 206 prevent fluid from flowing in the conduits in anydirection but from the fluid inlet 200 toward the fluid outlet 220.

When the pump shaft 60 moves more into the cavity 212 and out of cavity210, a negative pressure is created in the cavity 210, drawing fluidfrom the inlet conduit 202 into the cavity 210. At the same time, apositive pressure is created in the cavity 212, pushing the fluidcontained therein into the outlet conduit 218 and fluid outlet 220.

FIG. 6A is a side, cross-sectional view of an embodiment of a volumetricpump similar to that illustrated in FIG. 6, but with a different drivesystem which eliminates the need for a drive shaft entering the housing.In FIG. 6A, drive coils 230 and 232 are disposed around the cavities 210and 212, respectively, each coil comprising in the preferred embodimenta series of conductive wires wrapped around the housing 208 defining thecavities. Wires 234 connect the coils to sources of electrical current(not shown).

A pump shaft 236, disposed in the cavities 210 and 212 and through anaperture 24 in sheet of material 20, is preferably constructed offerro-magnetic or permanent magnet material. When the coil 230 issupplied electrical current through the wires 234, it creates a magneticfield which draws the pump shaft 236 into the cavity 210, as will beapparent to those skilled in the art, until it reaches a fixed permanentmagnet 238. In the preferred embodiment, the fixed magnet 238 serves tokeep the shaft in position without assistance from the coil 230.Electrical current to the coil 230, therefore, is supplied onlymomentarily to initially draw the shaft into the cavity 210.

Similarly, when the coil 232 is momentarily energized, it creates amagnetic field which, in the preferred embodiment, overcomes the forceof the magnet 238 against the shaft 236 and draws the shaft into thecavity 212 until it reaches a fixed permanent magnet 240, which keepsthe shaft in position.

The selective energizing of the coils 230 and 232 thus moves the shaftin a reciprocating movement, pumping fluid similarly as in theembodiment of FIG. 6.

FIG. 6A further shows diaphragms 242 and 244 made of resilient materiallocated at the ends of the housing 208. The diaphragms have some give inthem and each bows outwardly when the shaft moves toward it withsufficient force, creating positive pressure in the cavity; for example,diaphragm 242 bows outwardly when the shaft moves into cavity 210.Likewise, each diaphragm moves inwardly when the shaft moves away fromits corresponding cavity, creating a negative pressure. The diaphragmslessen the pressure in the cavities caused by movement of the shaft,allowing the shaft to move quickly from one side to the other withoutpower loss in the drive coils 230 and 232 in cases where the inletand/or outlet conduits are long or otherwise restrictive to fluid flow.

As will be apparent to those skilled in the art, the diaphragms can bemade more or less compliant depending on the degree to which thepressure caused by shaft movement is desired to be modified. Thediaphragms may also be added to other embodiments of the volumetric pumpdescribed herein.

FIG. 6B is a fragmented, side, cross-sectional view of a furtherembodiment of a pump similar to that illustrated in FIG. 6, but againwith a different drive system. In this embodiment, the housing 208contains three cavities: the cavities 210 and 212 in their usualpositions at the juncture of the inlet and outlet conduits, and anadditional interior cavity 252 between the cavities 210 and 212, eachcavity separated from the other by a resilient sheet 20 with an aperturethrough which the pump shaft 60 passes, forming sphincter seals in themanner previously described.

The interior cavity 252 is not used to pump fluid. Rather, it houses aslider 254, preferably cylindrical with a bore through its center andthrough which the shaft 60 passes. The slider 254 is made offerro-magnetic or permanent magnet material, disposed coaxially aroundthe pump shaft 60, and has recesses 258 and 260 on either end adjacentthe pump shaft. Drive coils 230 and 232 and magnets 238 and 240 areprovided to move the slider 254 back and forth in the same manner ofmoving the shaft 236 back and forth in FIG. 6A. The shaft 60 in FIG. 6Bpreferably is non-magnetic in order not to be affected by the coils andmagnets.

The slider 254 is positioned on and connected to the pump shaft 60 bymeans of flanges 262 and 264 extending outwardly from the shaft nearopposite ends, and coil springs 266 and 268 disposed respectively in therecesses 258 and 260 around the shaft and between the flanges and theslider. The spring 266 urges the slider 254 away from the flange 262,and the spring 268 urges the slider away from the flange 264.

In operation, when the coil 230 is energized (by an electrical currentsource not shown) it draws slider 254 in the direction of the cavity 210until it abuts the magnet 238, which holds it in position. The sliderapplies directional force to the pump shaft 60 through the spring 266,causing the shaft to move into the cavity 210. By its nature, the springis compliant and will lessen the momentary force of the shaft relativeto the slider, slightly lessening the momentary positive pressure in thecavity 210 and negative pressure in the cavity 212. The springs 266 and268 thus perform the same function as the diaphragms 242 and 244 in FIG.6A.

When the coil 232 is energized it overcomes the force of the magnet 238and draws the slider 254 in the direction of the cavity 212 until theslider abuts the magnet 240, which holds the slider in position. Theslider 254 applies directional force to the shaft 60 through the spring268 in the same manner as above described.

FIG. 6C is a fragmented, side, cross-sectional view of a furtherembodiment of a pump similar in all respects to the embodiment of FIG.6A except that a pump shaft 236 is driven by a single elongate annularmagnet 280 instead of by coils 230 and 232 and magnets 238 and 240. Themagnet 280 is slidably disposed around the housing 208 and is moved backand forth by any suitable mechanical means such as the drive mechanismsof FIGS. 1 and 3. As the magnet moves toward the cavity 210, it drawsthe shaft 236 toward the cavity 210 by magnetic attraction, and as itmoves toward the cavity 212, it draws the shaft 236 toward the cavity212 by magnetic attraction.

FIG. 7 shows a side, cross-sectional view of a valve using sphincterseals in accordance with the invention. In this embodiment, an elongatehousing 292 is formed of suitable rigid material with a closed end 294.The other end is closed by a resilient sheet of material 20 with anaperture 24 through which a shaft 60 passes, forming a sphincter seal inthe manner previously described.

A second sheet of resilient material 20a with an aperture 24a isdisposed within the housing 292, dividing it into two cavities 296 and298, with the aperture 24a serving as a passage therebetween. Unlikeprevious embodiments of sphincter seals, the shaft 60 passes onlyselectively, rather than continuously, through the aperture 24a.

A fluid inlet 300 is formed in the housing 292 leading into the cavity296, and a fluid outlet 302 is formed in the housing leading from thecavity 298. A fluid source 304 is connected to the fluid inlet 300, anda fluid sink 306 is connected to the fluid outlet 302. One or both ofthe source 304 and sink 306 is pressurized to urge fluid from the sourceto the sink through the valve.

In operation, when the shaft 60 is withdrawn from the aperture 24a bymovement toward the cavity 296, the aperture serves as a passage betweenthe cavities 296 and 298, allowing fluid to flow from the fluid source304, through the inlet 300, into the cavity 296, through the aperture24a, into the cavity 298, through the outlet 302, and into the fluidsink 306. When the shaft 60 is placed into the aperture 24a by movementtoward the cavity 298, a sphincter seal is formed and communicationbetween the cavities 296 and 298 is blocked, stopping fluid flow. Inthis manner, the structure of FIG. 7 operates as a valve.

FIG. 8 shows a side, cross-sectional view of another embodiment of avalve using sphincter seals according to the invention, which can beused to switch fluid flow from one destination to another, or stop flowaltogether. In this embodiment, a housing 310 is divided into threeinterior cavities 312, 314, and 316 by two sheets of resilient material20 and 20a, each having an aperture 24 and 24a, respectively. Anelongate shaft 60 moves back and forth through the cavities andapertures, driven by a drive shaft 318 which passes through an aperture24b in a sheet of resilient material 20b disposed in an opening 311 inthe side of the housing 310, forming a sphincter seal as previouslydescribed. An inlet conduit 320 leading from a fluid source (not shown)leads into the middle cavity 314. Outlet conduits 322 and 324 lead outof cavities 312 and 316, respectively, to fluid sinks (not shown).Either the fluid source or fluid sinks, or both, are pressurized to urgefluid from the source to the sinks. The shaft 60 selectively passesthrough the apertures 24 and 24a, selectively forming sphincter sealsand blocking fluid flow between the cavities. The shaft 60 may be madelong enough to enable it to pass through both apertures 24 and 24a atthe same time, completely blocking fluid flow, or may be made shorter sothat it is unable to pass through both apertures at the same time.

In operation, when the shaft 60 moves toward the cavity 312, it passesthrough the aperture 24, forming a sphincter seal therein and blockingfluid flow between the cavities 312 and 314. At the same time, the shaft60 comes out of the aperture 24a, opening the aperture and enablingfluid to flow from the inlet cavity 314 into the cavity 316 and throughthe outlet conduit 324 to the fluid sink. When the shaft 60 moves towardthe cavity 316, it passes through the aperture 24a, forming a sphincterseal therein and blocking fluid flow between the cavities 314 and 316.At the same time, the shaft comes out of the aperture 24, opening theaperture and enabling fluid to flow from the inlet cavity 314 into thecavity 312 and through the inlet conduit 322 to the fluid sink. If theshaft has been made long enough, it may be centered in the cavity 314,passing through both apertures 24 and 24a and blocking all fluid flow.

FIG. 9 shows a side, cross-sectional view of a spool valve mechanism forcontrolling the flow of fluid, combined with a pump similar to that ofFIG. 3. This embodiment of the invention comprises a housing 320containing an interior cavity 322. An elongate valve shaft 324 isdisposed inside the cavity 322, and an elongate drive shaft 326, ofsmaller diameter than the valve shaft 324 in the preferred embodiment,is connected to one end of the valve shaft. The drive shaft 326 passesthrough a passage 328 formed in the housing to extend from the cavity322 to the exterior. A resilient sheet of material 20 having an aperture24 is disposed on the housing on the exterior side of the passage 328,and the drive shaft 326 passes through the aperture to form a sphincterseal as previously described. The drive shaft 326 can be used to movethe valve shaft 324 back and forth in a reciprocating motion, or merelyto stabilize the valve shaft in position, or simply not be used orremoved from the apparatus.

The valve shaft 324 includes two flanges 330 and 332 spaced apart fromone another. The flanges may extend only partially around thecircumference of the valve shaft 324, as shown, or completely around, ifdesired, though in the latter case, the bottom of the cavity 322 wouldneed to be lowered from what is shown in the drawing.

A piston 334 is disposed in the cavity above the valve shaft 324 andsubstantially parallel thereto. A tab 336 extends downwardly from thepiston sufficiently far to abut either of the flanges 330 or 332 whenthe piston is moved longitudinally a sufficient distance. The piston 334extends from the cavity to the exterior of the housing 320 through apassage 338 formed in the housing. A resilient sheet of material 20a,with an aperture 24a, is disposed across the passage 338, and the pistonpasses through the aperture to form a sphincter seal as previouslydescribed.

An inlet conduit 340 passes through the housing into the cavity 322,near the connection of the valve shaft 324 to the drive shaft 326. Aresilient sheet of material 20b, with an aperture 24b, is disposedacross the inlet conduit substantially parallel to the sheet 20, withthe apertures 20 and 20b aligned along the drive shaft 326. The aperture24b is larger than the aperture 24, enabling the drive shaft 326 to passthrough the aperture 24b without forming a sphincter seal, though theaperture 24b is small enough to form a sphincter seal with the valveshaft 324 when the latter passes therethrough.

An outlet conduit 342 passes through the housing into the cavity 322near the opposite end of the valve shaft 324 from the inlet conduit 340.A resilient sheet of material 20c with an aperture 24c, of approximatelythe same size as the aperture 24b and aligned therewith, is disposedacross the outlet conduit substantially parallel to the sheet 20b. Thevalve shaft 324 selectively passes through the aperture 24c, forming asphincter seal therewith when passing through it.

The inlet and outlet conduits are attached to a fluid source and a fluidsink, respectively (not shown).

The valve shaft 324 may be made long enough so that when it is centeredbetween the sheets 20b and 20c it passes through both correspondingapertures 24b and 24c and forms sphincter seals with both.Alternatively, the shaft may be made short enough so that when centeredbetween the two sheets it passes through neither aperture. The valveshaft may be moved back and forth by either the drive shaft 326 attachedto suitable drive means, or the piston 334 attached to suitable drivemeans. If moved by the piston 334, the shaft 324 is moved in thefollowing way: to cut off fluid flow to the outlet conduit 342, thepiston is moved toward the outlet conduit until the tab 336 abuts theflange 332 on the valve shaft 324 and pushes the shaft into the aperture24c. To cut off fluid flow from the inlet conduit 340, the piston ismoved toward the inlet conduit 340 until the tab 336 abuts the flange330 on the valve shaft 324 and pushes the shaft into the aperture 24b.The location of the drive shaft 326 through the aperture 24b does notprevent fluid flow from the inlet conduit into the cavity since, aspreviously noted, the aperture is of a larger diameter than the driveshaft. The positive and negative pressures required to cause fluid flowfrom the fluid source into the cavity 322, and from the cavity 327 tothe fluid sink are produced by the motion of the piston 334, i.e., apumping action.

FIGS. 10, 11, 12, 13 and 13A show five illustrative embodiments of drivemechanisms which may be used to drive the pump or valve shafts of thepresent invention.

FIG. 10 shows a side view of a drive mechanism which includes anelongate drive shaft 350 attached to a pump or valve shaft 60, with anotch 352 cut on the bottom of the drive shaft 350. A ramp 354containing a shoulder 356 is disposed beneath the drive shaft 350. Theshoulder 356 divides the ramp into a lower portion 354a and a higherportion 354b. Rollers 358 or other suitable adjustment means aredisposed on the underside of the ramp to allow adjusting itslongitudinal position to thus vary the stroke length of the pump shaft60, as described below. A secondary driver 360 is disposed on rollers362 which rest on the lower portion 354a of the ramp. A tab 364 extendsupwardly from the forward end of the secondary driver nearest theshoulder 356. A disc 366 given rotary motion by a motor or other drivemeans connects to the end of the secondary driver opposite the tab 364by a rod 368, which is pivotally attached at one end to the disc and atthe other to the secondary driver. The rotary motion of the disc 366moves the secondary driver 360 back and forth in a conventional manner.

In operation, when the secondary driver 360 moves forward, it does notcontact the drive shaft 350 until the rollers 362 reach and move up theshoulder 356, forcing the secondary driver 360 upwardly and the tab 364into the notch 352, causing the drive shaft 350 to be moved forwardlywith the secondary driver 360. When the secondary driver 360 movesrearward, it forces the drive shaft 350 rearward by way of the tab/notchconnection until the rollers 362 move down the shoulder 356, causing thetab 364 to come out of the notch 352, breaking the connection andstopping movement of the drive shaft 350.

As will be apparent to those skilled in the art, the notch 352 mustinitially be placed in position to receive the tab 364 when the latteris elevated by the shoulder 356.

The stroke of the drive shaft 350 may be easily adjusted by moving theramp 354 forwardly or rearwardly. If the ramp is moved rearwardly (withappropriate adjustment of the drive shaft 350 to align the notch), thetab 364 enters the notch earlier in the forward movement of thesecondary driver 360, moving the drive shaft farther forward, andcorrespondingly farther rearward. If the ramp is moved forwardly, thetab enters the notch later in the forward movement of the secondarydriver 360, moving the drive shaft a lesser distance forward and acorrespondingly lesser distance rearward.

Varying the stroke of the drive shaft 350 adjusts the flow rate of thepump while allowing the driver to be run at a constant rate. Othercontrol or drive mechanisms may be used to accomplish the same end(i.e., adjust the flow rate) such as variable speed drive mechanisms,and variable delay of constant speed drive mechanisms.

FIG. 11 shows another drive mechanism comprising a pump or valve shaft60 driven by a drive shaft 372 having teeth 374 on one side. A wheel 376having teeth 378 spaced circumferentially therearound engages the teeth374, converting rotary movement of the wheel into longitudinal movementof the drive shaft. The rotary movement of the wheel reverses directionto reverse direction of the drive shaft.

FIG. 12 shows another drive mechanism comprising an elongate drive shaft380 connected to a pump or valve shaft 60. The drive shaft 380 has athreaded interior recess 382 into which a threaded rod 384 fits. The rodis caused to rotate by a motor 386. Depending on the direction ofrotation, the rotational motion of the rod 384 moves the drive shaft 380back or forth.

FIG. 13 shows a perspective view of another drive mechanism for a pumpshaft 60 attached at one end to a rigid anvil 390 which is oval-shapedin side cross section. A flexible filament 392 made of suitably strongmaterial is wrapped snugly around the anvil, with a loop of the filamentwrapped around a drive shaft 394 which is given rotational motion by amotor 396. As the drive shaft rotates to thus move the filament 392, theanvil and thus the pump shaft are caused to move longitudinally, as thedrive shaft 394 gathers in and lets out filament 392 to accommodate itsrotational movement, the manipulated filament forces the anvil to movein turn.

FIG. 13A shows a plunger 60 driven by a drive shaft 430 which ispivotally connected at an outer end 60a to an end 432 of the driveshaft. A crank 434 is pivotally connected to the other end 435 of thedrive shaft 430. The crank is rotated by any suitable means, moving thedrive shaft 430 in a reciprocating fashion and thus the plunger 60 backand forth in longitudinal movement. Preferably, sphincter seals asdescribed above are formed at fluid interfaces with the components.

FIGS. 14 through 16 show fluid pressure detectors for use, for example,with the volumetric pumps of the present invention to detect whenpressure exceeds a certain level or falls below a certain pressure.

In FIG. 14, a fragmented, side, cross-sectional view, a housing 400 isformed with an interior cavity 402 which is bisected by a conventionalcompliant diaphragm 404. A flexible conductive disc 405 is disposed ontop of the diaphragm 404. Two conductivity sensors 466 are disposed atthe top of the cavity 402.

An inlet conduit 408 leads into the cavity 402 from a fluid port 410. Asfluid pressure in the port increases, the fluid entering the cavitycauses the diaphragm 404 to bow upwardly, until at a predeterminedpressure it bows sufficiently far to cause the conductive disc 405 tocontact the conductivity sensors 406, electrically shorting them toindicate overpressure in the port.

In FIG. 15, which is also a fragmented, side, cross-sectional view, afluid port 412 includes an opening 414 through its wall and a diaphragm404 covering the opening. A T-shaped lever 416, pivotally attached atone end to a stationary point 419, with arms 416a and 416b disposedbetween and contacting at their ends the diaphragm 404 and a flexibleconductive dome contact 418. The dome contact is disposed on a support420. A conductivity sensor 406 is positioned on the support in alignmentwith the dome contact.

As fluid pressure in the port 412 increases, the fluid entering theopening 414 causes the diaphragm 404 to bow upwardly, causing, throughthe arms 416a and 416b of the lever 416, the dome contact 419 to flattenagainst the support 420. At a predetermined pressure, the diaphragm bowssufficiently far to cause the dome contact 419 to flatten and contactthe conductivity sensor 406, indicating overpressure in the port 412.

FIG. 16 shows a fragmented, side, cross-sectional view of a detector fordetecting underpressure of fluid in a port 412 (instead of overpressureas in FIGS. 14 and 15). In FIG. 16, an opening 414 is formed withshoulders 422 to limit upward bowing of a diaphragm 404 disposed in theopening. A coil spring 424, together with normal fluid pressure in theport 412, urges the diaphragm 404 against arm 416 which flattens a domecontact 419 to contact a conductivity sensor 406.

If fluid pressure in the port 412 decreases to a predetermined point,the diaphragm 404 begins to flatten toward the port, causing the domecontact 419 to break its connection with the conductivity sensor 406,indicating underpressure in the port.

FIGS. 17 and 18 show respectively a side, cross-sectional view, and aview taken along lines 18--18 of FIG. 17, a ball valve for use withvolumetric pumps of the present invention, among other mechanisms. Theball valve comprises a housing 440 defining therein two adjacentcavities 442 and 444 (FIG. 18) having a passage 446 therebetween. Aninlet conduit 448 leads into the cavity 442 from the exterior of thehousing, and an outlet conduit 450 leads from the cavity 444 to theexterior of the housing on the opposite side of the housing from theinlet conduit. Walls 454 separate the cavities from the exterior andeach other.

A resilient sheet of material 456 (FIG. 17) made of, for example, latexor silicone rubber, is disposed over the cavities and is pressed againstthe walls 454 by a top portion 440a of the housing 440, sealing thecavities against fluid communication with the exterior or with eachother except through the passage 446. An aperture 458 is formed throughthe top portion 440a of the housing to extend down to the sheet 456 inalignment with the passage 446, and a ball 460 is disposed in theaperture.

In operation, fluid from the inlet conduit 448 flows into the cavity442. When the valve is in open position (shown in FIG. 17), the fluidcontinues through the passage 446 into the cavity 444 and out the outletconduit 450. To close the valve, the ball 460 is pushed down, forcingthe sheet 456 to bend downwardly into the passage 446, sealing it fromfluid flow. This action stops fluid flow between the cavities.

FIG. 19 shows a fragmented, side, cross-sectional view of a plunger"bottoming" detector using the principles of the present invention. Agenerally elongate housing 470 includes therein an elongate cavity 472which is divided into adjacent compartments 472a and 472b by a resilientsheet of material 20 containing an aperture which forms a sphincter sealwith a shaft or plunger 60 as previously described. A passage 474connects the compartment 472b with a fluid chamber 476 having anaperture 478 through which is disposed a rod 480 having a piston 482disposed on one end in the fluid chamber 476. The other end 480a of therod 480 is preferably operatively connected to a valve or switch (notshown).

The bottoming detector of FIG. 19 is designed to detect when the plunger60 reaches the end of a stroke, or, alternatively, if it has gone beyondthe anticipated reciprocating distance, to take appropriate action. Inoperation, the plunger 60 moves in reciprocating motion. When its end60a reaches the sheet 20, it forms a sphincter seal with the sheet. Uponfurther motion into the (fluid-filled) compartment 472b, fluid is forcedfrom the compartment through the passage 474 and into the fluid chamber476, increasing pressure in the latter and urging the piston 482 towardthe aperture 478, moving the rod 480 and activating the valve or switchto which it is connected. Thus, movement of the plunger 60 beyond thesheet 20 may be detected to alert a user.

FIG. 20 shows another embodiment of a valve according to the invention,comprising a generally elongate housing 490 defining an elongateinternal cavity 491 with three sheets of resilient material 20a, 20b,and 20c disposed therein, each sheet containing an aperture forformation of sphincter seals, as previously described. The sheets 20a,20b, and 20c are spaced from each other, forming four fluid compartments490a, 490b, 490c, and 490d in the cavity 490. A plunger 60 is disposedin the cavity through the aligned apertures in the sheets, formingsphincter seals therewith. The shaft contains an internal passage 492running partially along its length with spaced openings 494 and 496 ateach end of the passage, in fluid communication with the cavity.

An inlet 498 is formed through the housing wall into the compartment490b, and an outlet 500 is formed through the housing wall into theadjacent compartment 490c. The openings 494 and 496 are spaced such thatwhen the opening 494 is located in the compartment 490b, the opening 496is located in the compartment 490c, providing fluid communication fromthe inlet 498, through the compartment 490b, opening 494, passage 492,opening 496, and compartment 490c to the outlet 500. When the plunger ismoved, the openings are moved from their respective positions in thecompartments 490b and 490c, blocking communication between the inlet andoutlet. This, of course, defines typical valve operation.

The apparatus of FIG. 20 can also be used to direct fluid received, forexample, at the left side of the apparatus (indicated by arrow 493)either to inlet 498 (which would become an outlet) or to outlet 500.This would be done by positioning shaft 60 with the opening 496positioned in compartment 490b so that fluid would flow from compartment490a through opening 494 and passage 492, out opening 496 intocompartment 490b, and out the "outlet" 498. To direct fluid out theoutlet 500, the passage 492 would be long enough to allow positioningopening 496 in compartment 490c while opening 494 is still positioned incompartment 490a. Then, with opening 496 positioned in compartment 490c,fluid would flow through opening 494 and passage 492, out the opening496 into compartment 490c, and then out the outlet 500.

FIG. 21 shows another embodiment of a seal suitable for use in certainapplications of pumps or valves of the present invention. In someapplications, this seal may be used instead of a sphincter seal aspreviously described. As in previous embodiments of the invention, agenerally elongate housing 510 defines an interior cavity 512 which maybe configured for the particular pump or valve application, such as withinlet and outlet passages 514 and 516. A shaft or plunger 60 is disposedin the cavity and lengthwise aligned therewith.

A portion 510a of the housing is configured to have a very close fitwith the shaft 60, with just enough space between them to allow theshaft to slide in reciprocating movement back and forth in the cavity.The housing portion 510a is thicker than the resilient sheets used forsphincter seals in previous embodiments, and is preferably made of morerigid material such as glass, sapphire or metal. The seal formed betweenthe housing portion 510a and the shaft, therefore, is not complete andleaks slowly. However, if the pump action is fast enough the leakage iscomparatively insignificant and the seal is satisfactory.

The seal of FIG. 21 can be used in place of any sphincter sealpreviously described in connection with apparatuses of the presentinvention if the volume of fluid flowing through the apparatus is largecompared to the leakage through the seal or the leakage is otherwisedeemed unimportant to the operation of the apparatus.

FIGS. 22 and 23 show a top view and side, cross-sectional viewrespectively of a programming card system for controlling the drivesystems of the present invention. The embodiment shown in FIGS. 22 and23 show only one of many ways of controlling the driving of the shaftsor other moveable parts in embodiments of the present invention, such asthe amplitude and frequency of the shaft's reciprocating movement. Othermeans of communicating the "program" to a system controller includeswitches, including rotary switches, bar code readers, and electroniccommunication from a programming unit to the driver unit, etc. However,the programming card system of FIGS. 22 and 23 is especially convenientfor programming an IV pump controller, such as the control unit 118 ofFIG. 3. A physician or pharmacist could readily prepare a card (as willbe discussed momentarily) to control the parameters and operational modeof an IV pump as required for a particular patient.

The programming card system of FIGS. 22 and 23 comprises a programmingcard 520 containing selectively punched holes 522 (punched, for example,by a physician or pharmacist) and index tracks 524. The holes and tracksare arranged in columns and rows. The card is designed for placement ina card reader 526, which comprises a series of conductive fingers 528which are mounted on and biased against a printed circuit board 529 orequivalent structure which contains traces 530 electrically connected toa control unit or circuit 532. The traces are disposed beneath theportion of the fingers which contacts the board 529, and detect when thefingers contact the board.

In operation, the holes and index tracks in the programming card arealigned with the fingers 528. When the card is fed into the reader 526the holes, which are selectively chosen on the card, allow contactbetween the fingers and the traces, while other portions of the cardwhich have not been punched out do not allow the electrical connectionto be made, thus allowing the reader to interpret the information on thecard and appropriately program the controller for the driver of theapparatus of the present invention.

FIG. 24 shows a fragmented, side, cross-sectional view of a sphincterseal, including a shaft 60 disposed in an aperture 24 formed in a sheetof flexible material 20. In this embodiment, a lip 602 of the aperture24 of the sheet of material 20 is formed to turn inwardly toward theinterior of the pump housing (not shown) to effectively lie snugly abouta portion of the shaft 60. A coil spring 606 is disposed about the lip602 to urge the lip tightly against the shaft 60 to further enhance theseal between the sheet of material 20 and the shaft 60.

FIG. 25 shows a fragmented, side, cross-sectional view of a duplexsphincter shield arrangement, including a shaft 60, a first flexiblesheet of material 620 having an aperture 624 formed therein, and asecond sheet of flexible material 628 having an aperture 632 formedtherein. A lip 636 of the aperture 624 of the sheet of material 620 isturned inwardly as shown, as is a lip 640 of the aperture 632 of thesheet of material 628, so that the lips are facing inwardly towards oneanother. A ring 644 is disposed between the sheets of material 620 and628 to define a substantially airtight cavity 648 between the sheets ofmaterial 620 and 628, the ring 644, and the shaft 60.

With the configuration of FIG. 25, when the shaft 60 is movedlongitudinally in either direction, the sheets of material 620 and 628are flexed to increase the pressure in the cavity 648 and force the lip636 and 640 in tighter contact with the shaft 60.

FIG. 26 is a fragmented, side, cross-sectional view of a duplexsphincter seal arrangement again including a shaft 60, a pair offlexible sheets of material 650 and 654, each with apertures 658 and 662respectively, for receiving the shaft 60. However, instead of lips 664of the sheet of material 650, and 668 of the sheet of material 654,turning inwardly towards one another as in FIG. 25, the lips are turnedoutwardly away from one another as shown. A ring 672 is disposed betweenthe sheets of material 650 and 654 to define a cavity 676 similar to thecavity 648 of FIG. 25.

In operation, when the shaft 60 of the seal arrangement of FIG. 26 isreciprocated in either direction, a vacuum is produced in the cavity 676so that outside pressure acts to force the lips 664 and 668 in tightercontact with the shaft 60, as desired.

The embodiments of the invention described herein are only examples ofhow the invention may be applied to specific devices. Modifications andvariations of, for example, materials used, sizes and shapes ofcomponents, and equivalent structures will be apparent to those skilledin the art while remaining within the scope of the invention.

What is claimed is:
 1. A pump for pumping fluids from a fluid source toa fluid sink comprisinga housing defining an elongate cavity therein,with an opening on one side of the housing adjacent to and incommunication with one end of the cavity, the other end being closed, aresilient sheet of material disposed over the opening in the housing,said sheet including an aperture positioned in alignment with the cavityat said one end thereof, an elongate shaft slidably disposed in theaperture so that one end of the shaft extends into the cavity and theother end extends out of the housing, said aperture having substantiallythe same cross-sectional shape as that of the shaft, and the samecross-sectional dimensions or smaller, inlet means for conveying fluidfrom the fluid source into the cavity when a negative pressure isproduced therein, outlet means for carrying fluid from the cavity to thefluid sink when a positive pressure is produced in the cavity, actuationmeans for causing the shaft to reciprocate longitudinally in the cavity,sliding back and forth in the aperture, to alternately produce anegative pressure and positive pressure in the cavity, and support meanson each side of the sheet of material adjacent the aperture forcontacting and preventing distending or collapsing of the sheet ofmaterial as the shaft slides through the aperture.
 2. A pump as in claim1 wherein said resilient sheet of material is a material selected fromthe group consisting of latex rubber, silicone rubber and nitrilerubber.
 3. A pump as in claim 1 wherein the end cross-sectional shape ofthe cavity is substantially the same as that of the shaft, but larger indimension to allow the flow of fluid between the shaft and cavitysidewall.
 4. A pump as in claim 3 wherein the inlet means is disposednear said one end of the cavity, and wherein the outlet means isdisposed near said other end of the cavity.
 5. A pump as in claim 1wherein the dimensions of the cross-section of the aperture are smallerthan the dimensions of the cross-section of the shaft.
 6. A pump forpumping fluids from a fluid source to a fluid sink comprisinga housingdefining an elongate cavity therein, with an opening on one side of thehousing adjacent to and in communication with one end of the cavity, theother end being closed, a resilient sheet of material disposed over theopening in the housing, said sheet including an aperture positioned inalignment with the cavity at said one end thereof, an elongate shaftslidably disposed in the aperture so that one end of the shaft extendsinto the cavity and the other end extends out of the housing, saidaperture having substantially the same cross-sectional shape as that ofthe shaft, and the same cross-sectional dimensions or smaller, inletmeans for conveying fluid from the fluid source into the cavity when anegative pressure is produced therein, outlet means for carrying fluidfrom the cavity to the fluid sink when a positive pressure is producedin the cavity, actuation means for causing the shaft to reciprocatelongitudinally in the cavity, sliding back and forth in the aperture, toalternately produce a negative pressure and positive pressure in thecavity, and wherein the actuation means includesmeans for selectivelyvarying the magnitude of the excursion of the reciprocating shaft, tothereby vary the rate of pumping of the fluid, means for alternatelypushing the shaft in a direction into the cavity, and releasing theshaft from being pushed, and biasing means for forcing the shaft in adirection out of the cavity when the shaft is released by the pushingmeans, and wherein said excursion varying means includes stop means forstopping the movement of the shaft in the direction out of the cavity atselectable distances.
 7. A pump as in claim 6 wherein said excursionvarying means includesdrive means moveable, in response to saidactuation means, in a reciprocating manner in a pathway generallyparallel with the direction of movement of the shaft, said drive meansincluding means for engaging the shaft at a location along the pathwaymoving toward the housing, to move the shaft with movement of the drivemeans, and for disengaging the shaft at said location along the pathwaymoving away from the housing, and means for selectively varying thelocation at which the drive means engages and disengages the drive shaftto thereby vary the magnitude of the excursion of the shaft.
 8. Avolumetric pump comprisingan elongate housing open at first and secondends and formed with a first chamber adjacent the first open end and asecond chamber adjacent the second open end, and including an openingconnecting the chambers, a resilient sheet of material disposed over thefirst open end, and including an aperture therein, a tubular plunger,one end of which is inserted through the aperture in the resilientsheet, into the first chamber, for carrying fluid to the first chamber,drive means for moving said one end of the tubular plunger toreciprocate in the first chamber, alternately toward and away from thehousing, first valve means disposed at said one end of the tubularplunger for allowing the flow of fluid therefrom when the plunger ismoved away from the housing to produce a negative pressure in the firstchamber, and for preventing the flow of fluid thereinto when the plungeris moved toward the housing to produce a positive pressure in the firstchamber, and second valve means disposed in the second chamber at saidopening between chambers to allow the flow of fluid from the firstchamber, through the opening, to the second chamber, and out the secondopen end when a positive pressure is produced in the first chamber, andto prevent the flow of fluid from the second chamber to the firstchamber when a negative pressure is produced in the first chamber.
 9. Avolumetric pump as in claim 8 wherein said first valve means comprises afirst plug and first biasing means for normally urging the first plug tocover said one end of the tubular plunger, and wherein said second valvemeans comprises a second plug and second biasing means for normallyurging the second plug to cover the opening between chambers.
 10. Avolumetric plump as in claim 8 wherein said tubular plunger issubstantially rigid at said one end, and for a predetermined distancerearwardly, and is substantially flexible from said predetermineddistance rearwardly.
 11. A volumetric pump comprisinga central hollowhousing open at opposite ends and having a first resilient sheet ofmaterial disposed in the housing between the ends to divide the hollowof the housing into two chambers, said sheet of material having anopening therein to allow communication between the two chambers, aninlet tubular section having a primary tubular portion for receivingfluid, and two secondary tubular portions branching from the primaryportion to each receive fluid therefrom, and terminating in free endsjoined to the housing, each near a respective opposite end of thehousing to carry fluid to a respective housing chamber, first and secondcheck valves, each disposed in a respective secondary tubular portion toallow the flow of fluid from the primary tubular portion toward thehousing, and to prevent flow in the opposite direction, an outlettubular section having two secondary tubular portions, each joined atone end to a respective opposite end of the housing to close the openends of the housing and carry fluid from a respective housing chamber,and having a primary tubular portion joined to the other ends of thesecondary tubular portions of the outlet tubular section, to receivefluid therefrom, third and fourth check valves, each disposed in arespective secondary tubular portion of the outlet tubular section, toallow the flow of fluid from the housing toward the primary tubularportion of the outlet tubular section, and to prevent flow in theopposite direction, elongate plunger means slidably disposed to extendthrough the opening in the first sheet of material so that portions ofthe plunger means reside in the two chambers, and means for selectivelymoving the plunger means back and forth in the two chambers toalternately produce negative pressure in one chamber and positivepressure in the other, and vice versa, to thereby cause fluid to flowfrom the inlet tubular section, through the housing to the outlettubular section.
 12. The pump of claim 11, further comprising a secondresilient sheet of material disposed over one open end of the housing,and having an opening therein, and wherein the plunger moving meansincludes a rod of smaller cross-sectional size than the plunger meansand joined at one end to one end of the plunger so that when the rod ismoved longitudinally, the plunger means is caused to movelongitudinally, said rod extending through the opening in the secondsheet of material.
 13. The pump of claim 11 wherein the plunger means ismade of a ferro-magnetic material, said pump further comprising firstand second electrically conductive drive coils disposed around thehousing adjacent the first and second chambers, respectively, and meansfor selectively supplying electrical current alternatively to the firstand second coils to draw the shaft more into the first and secondchambers, respectively.
 14. The pump of claim 13 further comprisingfirst means for temporarily holding the shaft in position in the firstchamber.
 15. The pump of claim 13 further comprising second means fortemporarily holding the shaft in position in the second chamber.
 16. Thepump of claim 11 wherein said housing includes first and second openingsat opposite ends thereof, said pump further comprising first and seconddiaphragms disposed over respective first and second openings.
 17. Thepump of claim 11 wherein the plunger means is made of ferro-magneticmaterial, said pump further comprising an annular magnet disposed aroundthe housing, said magnet being selectively moveable back and forth alongthe length of the housing for causing the plunger means to move back andforth in the hollow of the housing.
 18. The pump of claim 11 furthercomprising:a second resilient sheet of material disposed in the secondchamber to divide the second chamber into third and fourth chambers, thethird chamber being disposed between the first and fourth chambers, saidsecond sheet having an opening therein to allow communication betweenthe third and fourth chambers; first and second longitudinally spacedapart electrically conductive drive coils disposed around the housingadjacent the third chamber; means for selectively energizing the firstand second coils; an annular, magnetized slider with first and secondends disposed within the third chamber and connected to the plungermeans, the slider being movably responsive to the energized first orsecond coils such that it moves longitudinally within the third chambertoward the first chamber when the first coil is energized and toward thefourth chamber when the second coil is energized.
 19. The pump of claim18 further comprising a first recess at the first end of the slider anda second recess at the second end of the slider, first and secondlongitudinally spaced flanges on the plunger means adjacent the firstand second recesses, respectively, said first and second springs beingdisposed in the first and second recesses, respectively, between theslider and flanges.
 20. A pump for pumping fluids from a fluid source toa fluid sink comprisinga housing defining an elongate cavity therein,with an opening on one side of the housing adjacent to and incommunication with one end of the cavity, the other end being closed, aresilient sheet of material disposed over the opening in the housing,said sheet including an aperture positioned in alignment with the cavityat said one end thereof, an elongate shaft slidably disposed in theaperture so that one end of the shaft extends into the cavity and theother end extends out of the housing, said aperture having substantiallythe same cross-sectional shape as that of the shaft, and the samecross-sectional dimensions or smaller, inlet means for conveying fluidfrom the fluid source into the cavity when a negative pressure isproduced therein, outlet means for carrying fluid from the cavity to thefluid sink when a positive pressure is produced in the cavity, andactuation means for causing the shaft to reciprocate longitudinally inthe cavity, sliding back and forth in the aperture, to alternatelyproduce a negative pressure and positive pressure in the cavity, saidactuation means including means for selectively varying the magnitude ofthe excursion of the reciprocating shaft, to thereby vary the rate ofpumping of the fluid, and wherein the cavity and shaft haveapproximately the same cross-sectional shape and size except at said oneend in which the cavity is enlarged, and wherein the pump furthercomprising a trough formed in a wall of the cavity and running adjacentthereto and in fluid communication therewith substantially the length ofthe cavity, and wherein the inlet means and outlet means are in fluidcommunication with the enlarged portion of the cavity.
 21. The pump ofclaim 20 further comprising support means on each side of the sheet ofmaterial adjacent the aperture for contacting and preventing distendingand collapsing of the sheet of material as the shaft slides through theaperture.
 22. A pump as in claim 20 wherein said resilient sheet ofmaterial is a material selected from the group consisting of latexrubber, silicone rubber and nitrile rubber.
 23. A pump as in claim 20wherein the end cross-sectional shape of the cavity is substantially thesame as that of the shaft, but larger in dimension to allow the flow offluid between the shaft and cavity sidewall.
 24. A pump as in claim 23wherein the inlet means is disposed near said one end of the cavity, andwherein the outlet means is disposed near said other end of the cavity.25. A pump as in claim 23 wherein the dimensions of the cross-section ofthe aperture are smaller than the dimensions of the cross-section of theshaft.
 26. A pump as in claim 23 wherein said inlet means includesafirst conduit for conveying fluid from the fluid source to the cavity,and first check valve means disposed in the first conduit for allowingthe flow of fluid from the fluid source to the cavity, and forpreventing the flow of fluid from the cavity to the fluid source, andwherein said outlet means includesa second conduit for carrying fluidfrom the cavity to the fluid sink, and second check valve means disposedin the second conduit for allowing the flow of fluid from the cavity tothe fluid sink, and for preventing the flow of fluid from the fluid sinkto the cavity.
 27. A pump as in claim 20 wherein said inlet meansincludesa first conduit for conveying fluid from the fluid source to thecavity, and normally closed valve means responsive to said actuationmeans causing production of a negative pressure in the cavity foropening to allow the flow of fluid from the fluid source to the cavity,and wherein said outlet means includesa second conduit for carryingfluid from the cavity to the fluid sink, and normally closed valve meansresponsive to said actuation means causing production of a positivepressure in the cavity for opening to allow the flow of fluid from thecavity to the fluid sink.
 28. A pump as in claim 20 wherein saidactuation means includesmeans for alternately pushing the shaft in adirection into the cavity, and releasing the shaft from being pushed,and biasing means for forcing the shaft in a direction out of the cavitywhen the shaft is released by the pushing means, and wherein saidexcursion varying means includes stop means for stopping the movement ofthe shaft in the direction out of the cavity at selectable distances.29. A pump for pumping fluids from a fluid source to a fluid sinkcomprisinga housing defining an elongate cavity therein, with an openingon one side of the housing adjacent to and in communication with one endof the cavity, the other end being closed, a resilient sheet of materialdisposed over the opening in the housing, said sheet including anaperture positioned in alignment with the cavity at said one endthereof, an elongate shaft slidably disposed in the aperture so that oneend of the shaft extends into the cavity and the other end extends outof the housing, said aperture having substantially the samecross-sectional shape as that of the shaft, and the same cross-sectionaldimensions or smaller, inlet means for conveying fluid from the fluidsource into the cavity when a negative pressure is produced therein,outlet means for carrying fluid from the cavity to the fluid sink when apositive pressure is produced in the cavity, and actuation means forcausing the shaft to reciprocate longitudinally in the cavity, slidingback and forth in the aperture, to alternately produce a negativepressure and positive pressure in the cavity, said actuation meansincluding means for selectively varying the magnitude of the excursionof the reciprocating shaft, to thereby vary the rate of pumping of thefluid, and wherein said excursion varying means includes drive meansmoveable, in response to said actuation means, in a reciprocating mannerin a pathway generally parallel with the direction of movement of theshaft, said drive means including means for engaging the shaft at alocation along the pathway moving toward the housing, to move the shaftwith movement of the drive means, and for disengaging the shaft at saidlocation along the pathway moving away from the housing, and means forselectively varying the location at which the drive means engages anddisengages the drive shaft to thereby vary the magnitude of theexcursion of the shaft.
 30. A pump for pumping fluids from a fluidsource to a fluid sink comprisinga housing defining an elongate cavitytherein, with an opening on one side of the housing adjacent to and incommunication with one end of the cavity, the other end being closed, aresilient sheet of material disposed over the opening in the housing,said sheet including an aperture positioned in alignment with the cavityat said one end thereof, inlet means for conveying fluid from the fluidsource into the cavity when a negative pressure is produced therein,outlet means for carrying fluid from the cavity to the fluid sink when apositive pressure is produced in the cavity, an elongate shaft slidablydisposed in the aperture so that one end of the shaft extends into thecavity and the other end extends out of the housing, said aperturehaving substantially the same cross-sectional shape as that of theshaft, and the same cross-sectional dimensions or smaller, wherein thecavity and shaft have approximately the same cross-sectional shape andsize except at said one end in which the cavity is enlarged, and whereinthe inlet means and outlet means are in fluid communication with theenlarged portion of the cavity a trough formed in a wall of the cavityand running adjacent thereto and in fluid communication therewithsubstantially the length of the cavity, and actuation means for causingthe shaft to reciprocate longitudinally in the cavity, sliding back andforth in the aperture, to alternately produce a negative pressure andpositive pressure in the cavity.
 31. A pump as in claim 30 wherein saidresilient sheet of material is a material selected from the groupconsisting of latex rubber, silicone rubber and nitrile rubber.
 32. Apump as in claim 30 wherein the dimensions of the cross-section of theaperture are smaller than the dimensions of the cross-section of theshaft.
 33. A pump as in claim 30 wherein said inlet means includesafirst conduit for conveying fluid from the fluid source to the cavity,and first check valve means disposed in the first conduit for allowingthe flow of fluid from the fluid source to the cavity, and forpreventing the flow of fluid from the cavity to the fluid source, andwherein said outlet means includesa second conduit for carrying fluidfrom the cavity to the fluid sink, and second check valve means disposedin the second conduit for allowing the flow of fluid from the cavity tothe fluid sink, and for preventing the flow of fluid from the fluid sinkto the cavity.
 34. A pump as in claim 30 wherein said inlet meansincludesa first conduit for conveying fluid from the fluid source to thecavity, and normally closed valve means responsive to said actuationmeans causing production of a negative pressure in the cavity foropening to allow the flow of fluid from the fluid source to the cavity,and wherein said outlet means includesa second conduit for carryingfluid from the cavity to the fluid sink, and normally closed valve meansresponsive to said actuation means causing production of a positivepressure in the cavity for opening to allow the flow of fluid from thecavity to the fluid sink.